Syrian army defectors have attacked a major military base near Damascus, Syrian opposition groups say.

Parts of the Air Force Intelligence building in Harasta were reported to have been destroyed in the attack, but there were no reports of casualties.

It would be the Free Syrian Army’s most high-profile attack since Syria’s anti-government protests began.

The attack comes as the Arab League prepares to discuss its response to the crackdown on the unrest in Syria.

The Syrian government has severely restricted access for foreign journalists, and reports of violence are extremely difficult to verify.

The UN says more than 3,500 people have died since protests started in March. The Syrian authorities blame the violence on armed gangs and militants.

Army defectors have carried out a number of attacks on military targets in recent weeks but the Harasta incident, if confirmed, would be their most audacious so far.

Such an attack would be significant because Syria’s Air Force Intelligence is one of the most feared state agencies and has been involved in the suppression of protests against President Bashar al-Assad.

The base is also very close to the capital, which has remained relatively quiet in the unrest so far.

The BBC’s Jon Leyne, in Rabat for the Arab League meeting, says reports of the attack show how the situation in Syria is becoming more serious by the hour.

It is also a graphic illustration of how the conflict is moving close to being a civil war rather than a fight between unarmed protesters and the government, says our correspondent.
‘Several explosions’

The Syrian Revolution General Commission – one of a number of opposition groups involved in the Syrian National Council (SNC) – said the army defectors had attacked the building from three sides. Helicopters were also reported to have been hovering around the area.

A resident of Harasta told Reuters: “I heard several explosions, the sound of machine-gun fire being exchanged.”

The Local Co-ordination Committees also confirmed the attack, while the and the UK-based Syrian Observatory for Human Rights said targets in Zamalke, Hamuriya and Douma were also hit.

The Khaled ibn Walid Brigade, part of the Syrian Free Army, welcomed the attack in a statement, the AFP news agency reports.

“We pay tribute to our brothers, the rebel heroes, and may God bless your hands for your dawn operation targeting the intelligence building in Harasta,” it said.

The Free Syrian Army was formed by defectors opposed to Mr Assad a few months ago, and claimed to have 15,000 members by mid-October.

Its stated aim is to work alongside the Syrian people to topple the government and “stand up to the irresponsible military machine which is protecting the regime”.

The rebel army says more soldiers and officers are defecting every day but acknowledges it is not strong enough to take on the state’s military force.

On Tuesday, it was reported to have carried out an ambush in Deraa which left 34 government soldiers dead, according to Syrian activists.

November appears to be the bloodiest month of the eight-month revolt, with well over 300 people killed so far.

Mr Assad is coming under increasing international pressure to end the bloodshed.

The Arab League has already voted to suspend Syria’s membership, and will ratify the action at its meeting in Morocco on Wednesday.

Foreign ministers will also discuss other ways of increasing pressure on Mr Assad’s regime.

Syria, which will not attend the meeting, has condemned the suspension as “shameful and malicious”, accusing other Arab countries of conspiring with the West to undermine the regime.